Gravity and magnetic interpretation of the regional deep structure of the Vøring Basin

Abstract

The crustal structrue in the outer Vøring Basin is investigated by forward modelling of gravity data and interpretation of the magnetic field and the isostatic state. In addition all available magentic and gravity data for the Vøring Basin have been reprocessed. BP delivered depth-converted interpretation along six seismic profiles. These, together with the available results of OBS arrays, constrain the geometry of the structural models. The modelling has been done in 2D and where needed in 3D, Especially in the central and northern Vøring Basin, lateral changes in the density structures perpendicular to the seismic profiles had to be regarded to adjust the models.\rThe 2D and 3D models show that the gravity fields is mainly influenced by the thickness of the sediments, the depth of the Moho and the occurrence of magmatic underplating. The high density magmatic underplated material is probably related to the intrusion of sills from the Vøring Escarpment into the Vøring Basin and stops westwards of the Fles Fault Complex. To the east of the Fles Fault Complex normal lower crustal material is present instead.\rSeismic results show in the whole area deep crustal reflectors, which have been previously interpreted to be connected to magmatic underplating or top basement. The modelling results indicate that these reflections are connected to magmatic underplated structures and intracrustal reflectors. The modelling results are subsequently used to produce new maps of the depth to Basement and Moho.\rThe shape of the magnetic field in the outer Vøring area, suggests, in contrast to the gravity field, shallow sources, which are probably connected to igneous rocks. But in general the magnetic signature in the outer Vøring Basin shows no prominent anomalies. The main magnetic anomalies are caused by the transition to oceanic domains.